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INTRODUCTION
Thanks for buying the Percolator single-tube, 2-watt guitar amplifier kit from Zeppelin Design Labs! We
hope you will have fun assembling this kit, followed by many years of musical enjoyment. We think
we’ve produced a pretty nice product, and we’d love to hear your feedback. Send an email, or post
on the ZDL forum.
Note there is a serial number sticker on the chassis. Reference this serial number when and if you ever
need to contact us for assistance.
The Percolator was designed around a single tube developed by GE in the early 1960’s under the
brand name “Compactron.” Compactron tubes have multiple amplifier sections in one bottle. The tube
in the Percolator has two triodes and one sharp cut-off pentode. That’s the same topology as the Fender
Champ, but in one bottle! This tube was never intended to be used in an audio circuit (it was originally
designed for use in various parts of a TV circuit), but it works and sounds great in a guitar amplifier.
Since this tube is rarely, if ever, seen in guitar amps, it offers a rather unique tone.
Compactrons were developed in a time of fast technological growth. In the early 1960’s transistors were
becoming more stable and practical for use in more demanding circuits. They also were much smaller
and didn’t require as much power (via heating filaments). The tube market was being challenged and
threatened by this new solid state competitor. The GE corporation (which was one of, if not the most
prolific tube developers in the world at the time) was well invested in their miniature tube line and
wasn’t too interested in making the transition to transistor development. So to compete with transistors
and give tubes a few more years in the market, the engineers at GE developed the Compactron that
could take the place of several tubes with just one bottle. It was the tube equivalent to the integrated
circuit. They were mostly designed for use in the color TV market, but some of them did find their way
into radios and hifi amps. Ampeg even used a Compactron in some of their preamp circuits. GE made
a big push to promote and use these tubes in their products, but eventually transistors did win the
technology battle and tubes were altogether replaced in televisions, leaving large stockpiles of unused
Compactrons in warehouses. The last Compactrons were made in the early 1990’s and are still readily
available today as “new old stock” (NOS) items. The Percolator, with its single Compactron tube, gives
us a chance to re-purpose a piece of tube history, while offering unique tonality in this modern market.
CAUTIONS, WARNINGS, DANGERS
This is not a beginner’s electronics project! If you have not worked with line/high voltage electricity
before do not attempt this project without qualified help. THIS THING CAN KILL YOU if you don’t know
what you are doing. We expect that you know how to safely and properly solder electronics. If you
have never soldered a circuit board before, you MUST practice on something simpler and safer! If you
lack experience, build this kit with a qualified friend. Use common sense when soldering. Use safety
glasses and don’t burn yourself or anything else. We also expect you to know how to use a digital
multimeter (DMM). If you are not comfortable with using a DMM, either have an experienced friend
help you, or learn how by watching some YouTube videos on using a multimeter.
